The home of theoretical physics group and quantized musings blog at the University of Nevada, Reno

Monthly Archives: January 2013

"I attribute essentially all my success to the very large amount of chocolate that I consume. Personally I feel that milk chocolate makes you stupid.Now dark chocolate is the way to go. It's one thing if you want like a medicine or chemistry Nobel Prize, OK, but if you want a physics Nobel Prize it pretty much has got to be dark chocolate."

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With the on-going search for an experimental atomic physics faculty at the University of Nevada, Reno (UNR), I would like to provide a historical perspective on strong traditions of atomic physics at UNR.

"The physics faculty began building a solid record in atomic and molecular physics in the 1960s and improved on this foundation into the 1990s; Philip Altick, trained at Stanford and Berkeley, was an academic leader in this field for three decades and is recognized for initiating the department's high research standards. Colleagues Peter Winkler and Reinhard Bruch were attracted to UNR from Germany partly because of the important theoretical work under way here. Ron Phaneuf, department chair through most of the 1990s, was credited with advances in the program during that decade."

While Ron served as Department Chair, he established a program to study photoionization of ions at the Advanced Light Source in Berkeley. During that same period the UNR AMO program also grew. Faculty hires included Rami Ali, a recognized expert in experimental atomic collisions. After spending several years at UNR, Rami accepted an academic post in his native Jordan. Paul Neill collaborated on electron beam ion trap physics at Lawrence Livermore National Labotratory. Jeff Thompson has made important progress in measuring properties of negative ions and maintains that research program while serving as the Dean of College of Science at UNR.

Following Philip Altick’s retirement, a theorist, Andrei Derevianko, was hired. Andrei's interests are broad but primarily are in atomic clocks and in connecting atomic physics with particle and nuclear physics. Meanwhile, the entire field of AMO physics was being reshaped by advances in ultracold atom physics. Jonathan Weinstein was hired to expand in this important frontier. Jonathan uses cryogenically-cooled atoms and molecules to study cold collisions, cold chemistry, and quantum information. The most recent addition to the AMO program is Andrew Geraci. Andrew's experiments are in the rapidly growing fields of optomechanics, quantum precision sensors, and hybrid quantum systems.

if $guessed_energy >= 0.0 it is calculated internally from the hydrogenic formula
The guessed_energy for valence orbitals better be good, since the program gives some dumb answers if the hydrogenic default is used.$iof governs some internal step, the mixing weight between previous and next iteration

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One could rightfully state that the atomic-structure problem has been around for a very long time. Yes, this is true - in fact quantum mechanics has been invented to explain atomic properties. Then why do we still struggle to solve it?

Should we be embarrassed by our inability to solve this basic problem? Sure we can solve it approximately, but solving it accurately is another story.

So what is holding us back? It is the very same entanglement and complexity of Hilbert space (that is where wave functions live) that makes quantum computing so powerful. To illustrate this enormous complexity, I'll take my favorite atom, cesium. It has 55 electrons. With 3 degrees of freedom per electron (x, y, and z), the Cs wave function depends on coordinates. As a result of the calculation I would need to store the wave function. If I were to take a very poor grid of 10 points per coordinate, the storage would require $latex 10^{155}$ memory units.

$latex 10^{155}$ is of course an astronomically large number - in fact it exceed an estimated number of atoms in the Universe, . So even if we were able to compute the Cs wave function, there is no plausible way to store it in usable form.